How to fix audio sync for XLR microphones

If you’re using an XLR microphone (like the Shure SM7B) with Tella and noticing your audio is slightly ahead of your video, don’t worry — it’s easy to fix.

This guide walks you through setting up two small apps to sync your audio perfectly with your video recordings.

Why Does Audio Desync Happen?

XLR microphones process and deliver audio to your computer faster than your camera delivers video.

Typically, the audio arrives about 100 milliseconds earlier.

To fix this, we’ll add a small delay to the mic audio before it reaches Tella.

What You’ll Need

You’ll need two apps made by Rogue Amoeba:

• Audio Hijack – to add a delay to your microphone input

• Loopback – to create a “virtual microphone” that you can select in Tella

Both offer free trials, but you’ll need licenses for long-term use.

Step 1: Install Audio Hijack and Loopback

1. Download and install Audio Hijack and Loopback from Rogue Amoeba.

2. Open both apps — we’ll set them up next.

Step 2: Set Up Audio Hijack

1. Create a New Session in Audio Hijack.

2. Add an Input Device Block:

   • Choose your audio interface as the input (e.g., Scarlett 2i2, Apollo Solo, etc.).

   • Remember: you’re selecting the interface, not the mic itself.

3. Add a Sync (Delay) Block:

   • Drag in the Sync block.

   • Set the delay to -100 milliseconds.

   • This slows down your mic to match your camera timing.

4. Add an Output Device Block:

   • You’ll connect this to your virtual mic (set up in Step 3).

Step 3: Set Up Loopback

1. Create a New Virtual Device in Loopback.

2. Name it something like “Shure SM7B Sync” or “Tella Mic”.

3. Leave the default settings — it just needs to pass the delayed audio through.

Step 4: Connect Audio Hijack to Loopback

1. In Audio Hijack, for the Output Device, select the new virtual mic you created in Loopback.

2. Run the session.

   • You should see the audio flowing through the delay and into the virtual mic.

Step 5: Select Your Virtual Mic in Tella

When recording in Tella (or Zoom, Google Meet, etc.):

• Choose your new virtual microphone (e.g., “Tella Mic”) from the audio input options.

Your audio and video should now be perfectly in sync!

Quick Troubleshooting

• Audio still slightly off?

  Adjust the delay slightly (e.g., try -90ms or -110ms) in Audio Hijack.

• Apps need to stay open:

  Make sure Audio Hijack and Loopback are running in the background while recording.

Summary

1. Install Audio Hijack and Loopback

2. Add a 100ms delay in Audio Hijack

3. Route the delayed audio into a virtual mic with Loopback

4. Select the virtual mic in Tella

5. Record perfectly synced videos!